Telephone-transmitter.



G. ADAMS-RANDALL.

TELEPHONE TRANSMITTER.

APPLICATION FILED APR. 14,1905.

Patented Mar. 2, 1909.

Jag

I igwzedzw K2 and currents, without modification. plan views of different so ing CHARLES ADAMS-RANDALL, OF NEW YORK, N. Y.

TE LE PHONE -TRANSMIT TEE.

Specification of Letters Patent.

Patented March 2, 1909.

Application filed April 14, 1905. Serial No. 255,602.

To all whom 'it may concern:

Be it known that 1,, CHARLES ADAMS- RANDALL, a citizen of the United States, residing at New York, in the county of New 5 York and State of New York, have invented 1O mitters or apparatus for the electrical transmission of speech, and more es ecially to that class of transmitters adapte for use with common battery systems and currents of high potential, with means for, regulating o taining the proper resistance thereof, proportioned to the current em loyed, and

. the circuit used therewith, and a so embodying means in combination for obtaining and varying the requirednormal resistance for the 20 transmission of: articulate speech and other sounds.

The object of the invention is to produce a transmitter of novel construction having a high resistance without impairment of the 25 variability of the resistance mediruu and adapted more especially for the transmission of speech by the use of currents of higher voltage than usually employed with battery transmitters, such as regulated electric light detriment to the transmitter, and in a manner more economical and effective than by the use of dry batteries or electric currents of low voltage, as now generally racticed.

In ti l a part of the transmitter. Fig. 2 is a sectional elevation of the same. Fig. 3 is a view of the transmitter *embodyinga Figs; 4, 5, 6 and 7 illustrate forms of pads having elongated openings therein for containing the resistance granules and cooperating with the diaphragm, these pads being modifications of the granule holding meansshown in the receding figures.

Snnilar characters of reference are employed to indicate corresponding parts in the several views.

The numeral 1 designates the body or casof the transmitter which may be of any sultable material and has an upper. sectionz disposed thereon, as particularly shown by Fi s. 2 and 3. The body or casing 1 carries a 'aphragm 3, which rests u on a ring; 4 of rubber, paper or other suitahe material, the

formed means.

e drawings, Figurel is a plan view of diaphragm being held in place by any pre- The improved transmitter embodies the principle of increasing the normal internal resistance thereof and directly controlling said resistance without liability of packing of the resistance granules and without impairment of the variability of the latter, and thus materially increase the el'- fectivcncss of a granule resistance means in telephone transmitters.

Referring particularly to Figs. 1 and 2, the variable resistance consists in granules of carbon or other suitable material G. The granules are contained in an annular recess 25, formed in a felt or other analogous pad 26, held against the diaphragm 3 by any suitable means, the said recess 25 constituting a cell, seat or pocket of extended length, preferably of narrow width and shallow depth and in which thegranules are thinly spread over thd given area and separated at diametrically op osite points by insulating bridges 27, of vu ca'nite or analogous material. The pad 26, as shown by Fig. 4, is substantially similar to the pad 26, and may be substituted for the latter, and instead of using the insulating bridge 27 the material of the pad is continued at diametrically opposite oints, as at 26", to divide the pocket or seat 'or the carbon granules G into independent segmental members or parts. In Fig. '5, the pad 26 has but a single connecting web 26 etween the inner and outer portions thereof and the electrical contact is made with the carbon granules in the/pocket, cell or seat therefor in this form oi pad through the medium of suitable devices located at the ends P, P of the pocket, but, by preference, the electrical contacting or connecting means with respect to the granules will be of a form: ereinafter specifically referred to and shown by Fig. 2, and in the instance wherea switch is used, and which will be explained in connection with Fi 3. In Fig. 6, thepad 27 is further modi ed by preservingthe main portion thereof intact or imperforate and forming a diametric slot 27 therein to serve as a pocket or cell means for the retention of the resistance granules, contact with the granules being established at the ends oi said slot. The pad 28 shown by Fig. 7 is still further varied as to form a slot 28 which, in this instance/1s continuous almost entirely throughout the full body width by forming a "series of communicating oblong g eraser openings intersected by intermediate parti- 2 in proper position and is connected by a tions 28. This materially elongated pocket wire 41 with the bolt 30. A switch arm 32 is or cell to receive the resistance granules promovably supported on the member or pad 2 rides for the use of a larger quantity of the of the transmitter, and has its fclcrumed end 5 granules *ith increased resistance and iree-. connected by a wire 42 with the bolt 28. 70

dom irom packing, and in this form of the This switch arm 32 is shiftable between the transmitter by the movement'of the granules contacts 38 and (i0, and may be drawn over by theoperation or vibrations of the diaon to either one of the latter to connect the phragni a far greater variation of the variable different sets of separate, independent, disresistance is obtained than is possible when connected variable resistances severally, in 75 the granules are held in a deep receptacle. series, to graduate the resistance of the trans- The electrical contact with the granules in mitter to the required amount, and by which the pocket or cell, as constructed in the pad means the resistance of the transmitter is shown by Fig. 7, will be established at the regulated. in other Words, the movement diagonally opposed terminals of the slot, as of the switch arm 32-tothe contact 38 cuts 80 indicated at l, P. v out the materials or granules in one of the The construction shown by Figs. 1 and 2 pockets from the circuit, while moving the and the portions of the pads having elonswitch arm to the contact 40 places said regated openings for holding resistance gransistance material in both pockets in series in ules, as shown by Figs. 3, a, 5, 6 and 7, emthe circuit. I 85 bcdy the principle of increasing the internal Although a non-metallic diaphragm has resistance of the transmitter by-obtaining thus far been described as being preferred the variable resistance in a thin, elongated to render the transmitter more effective inor extended area, in contradistinction to an its operation, it will be understood that the increased depth of granules, whereby the improved transmitter is-not limited to the 90 liability .of packing by the resistance use of a non-metallic diaphragm, as a metal granules is overcome, thus materially -indiaphragm may be used, which may have the creasing the efl'ectiveness and variability of granules insulated therefrom. the granular resistance means in telephone in granular telephone transmitters of nortransmitters, and at the same time increasing mally high resistance it has been'customary 95 the-normal resistance and the totalresis'tance to obtain the normal variable resistance by when two or more separate, disconnected, the use of specially high resistance carbon independent variable resistances are used by granules arranged in a cup or receptacle connecting thesame in circuit, in series by having an increased depth to contain a suitable means. *reater mass of granules than ordinarily 190 ()ne of the preferred means of making 0011- used. This has been found obj actionable in tact with the granules at the ends of the. that the granules when so'arranged do not pocket or cell in its various forms, as just set permit of a great or, ready variation of the forth,'and' also for connecting the granules resistance, and they are also more liable to 40 in the pockets in circuit, in series, is shown pack whenthe variation becomes slight 105 by Figs. 2 and 3. This preferred cohor very nearly all. By the construction necting means consists of metal bolts 28,, 29, heretofore described and embodied in this 30 and 31, secured to the non-metallic or invention, the granules are held in an eloninsulating frame 2 of the transmitter by gated pocket, cell; seat, groove or recess, and v means of nut-s28, a second nut 28 being are disposed over greater) increased or 110 provided on each bolt for securing the wires lengthened area of proper dimensions and are or other connections to the several bolts. thinly spread, in contradistinction to the Each bolt is provided with a flat or thin head deep pocket or cup, so that the current passes 23, which rests upon and covers the granules over and through the granules in the direc .6 at the ends or the pockets and makes election of their length, or in the'directien of 115 trical contact with the said granules, as shown the length of the cell or pocket, the surface by Fig. 2, and owing to this arrangement the covered generally determining the normal cover must pass through or over the granules resistance in the pocket; By this particular from one end of the pocket to the other end, arran ement a maximum variation of the A the shaking up, disturbing, or vibrating granules is readily obtained from the vibra- 120 the granules by the variations of the dia--- .tion of the diaphragm or other vibrator phragm producing a variation in the reactuating them, and hence the said granules sistance' oiiered to the current passing thereare not likely to pack, and also permits the .throu h or thereover. As shown by Fig. 3, use of comparatively highvoltage current,

two 0? the bolts, for instance 29 and 31, are especially when several variable resistances 3.25 connected by wires 34 and 35, with terminals are connected up in circuit, in series; it 36 and 37, and extending also from the bolt, will also be understood from the disclosure 3? to a suitable switch point 38 on the memas to variation and shape of the pockets, as her 2 by a connecting Wire 39. A second well as separati n of the latter, that any switch point 40 is also secured on the member number of the pockets may be used and so connected up in series as to obtain the normal internal resistance desired, and it is also intended to adopt various other forms of pockets or cells and variable electrodes or resistances without departing from the general scope of the invention, and which is to rea ily obtaining and regulating the resistance, and of varying the said resistance for the transmission of articulate speech electrically when using a current of much higher voltage than now generall used.'

I Having thus described tile invention, what i is claimed, is:

1. A telephonic transmitter having an elongated receptacle means ofnarrow width and shallow depth, and a granular variable resistance in the said receptacle means, the

resistance of the said variable granular resista-nce being in the direction of its length in contradistinction to its depth.

2. A telephone transmitter characterized by having elongated receptacle means of narrow width and shallow" depth, and a granular variable resistance disposed in said receptacle means for increasing. the normal internal resistance of the transmitterythe parts-being so arranged that the current passes over or throughthe variable resisv ance in the direction of its length in contradistinction to-its depth.

3. A-telephone transmitter having therein two or more independent, disconnected, elongated receptacles, granular variable resistance material disposed in the receptacles,

and independent means for connecting up the latter. 4. A telephone transmitter ,having a plurailty of separate, disconnected, elongated receptacles, granular variable resistance material disposed in said receptacles, and independent means-for 'connectingnp the variable resistance material in the receptacles in circuit, in series.

dept the said resistancesbeing arranged in separate receptacles and the current passing len thwise over and through the resistances,

' an means for electrically connecting the re-.

sistances serially for the purpose. of increasing rovide a transmitter having means for' 5. telephone transmitter 'having'sep-. .arate, independent, electrically disconnected, .elon ated riable resistances --of shallow 7. A telephone transmitter having adiaphragm or vibrator, a plurality of independent granular resistances carried thereby and insulated therefrom and from each other, the resistance of the granules being in the direction of the length of the mass of the same, contact 'means' engaging the granular resistances at the extreme ends of .the extended mass of granules, and means for connecting said independent granular resistances in; circuit, in series, with each other, and a source of electric energy.

8. A telephone transmitter, having adiaphragm and vibrator, and a plurality of elongated receptacles containing resistance granules, the' granules being insulated from the diaphragm, and independent means for connecting two or more elongated receptacles in series with means for connecting such receptacles at their extreme ends to ob tain an increased resistance according to the length and in contradistinction to' the depth of t e receptacle. r

9. Means for increasing the normal in ternal resistance of a telephone-transmitter,

consisting in arranging variable granular resistance material over inn elon ated area and hav ng such materia of sha ow depth,

'the current passing solely over and through the resistance material in the direction of the length of said inateriaL'whereby the resistance ofthe material is increased without affecting its variability.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

CHARLES ADAMS-RANDALL. Witnesses:

H. CAWTHOBNE,

M. B. LOVELAOE. 

